POS0882 HIGH-RESOLUTION PERIPHERAL QUANTITATIVE COMPUTED TOMOGRAPHY FOR THE ASSESSMENT OF CALCINOSIS, ACROOSTEOLYSIS, AND PERIPHERAL BONE MINERAL DENSITY IN PATIENTS WITH SYSTEMIC SCLEROSIS: A CROSS-SECTIONAL PILOT STUDY
Authors: F. C. Enevoldsen, J. Therkildsen, R. Klose-Jensen, K. T. Aaen, A. L. Riis, K. Soendergaard, E. M. Hauge
Journal: Annals of the Rheumatic Diseases (2022)

Background Systemic Sclerosis (SSc) is a rare disorder associated with hand radiological damage, typically acro-osteolysis (AO) and calcinosis, and increased risk of osteoporosis [1, 2]. Recently, high resolution peripheral quantitative computed tomography (HR-pQCT) has contributed to advances in noninvasive imaging in patients with osteoporosis, inflammatory arthritis, and osteoarthritis. Due to its three-dimensional, high resolution (82 μm 3 ) imaging of calcified structures, HR-pQCT might be beneficial in detecting and describing early AO changes, calcifications or bone mineral density (BMD) loss and in studying potential treatment effects on progression/resolution of pathological manifestations. Objectives To study the association between different types of hand radiological damage assessed by HR-pQCT, and to evaluate volumetric BMD and microarchitecture at distal radius among SSc patients with and without AO. Methods This single-centre, cross-sectional study included patients with SSc according to ACR/EULAR 2013 recruited from the outpatient clinic at the Department of Rheumatology, Aarhus University Hospital, between 1st of October and 21st of December 2021. All patients underwent HR-pQCT (Xtreme CT, Scanco Medical AG) scan of the dominant hand’s distal radius and both hand’s distal phalanges (DP) on the 2 nd to 4 th finger. A semiquantitative scale of 0-3 was composed to quantify the degree of soft tissue calcifications identified in the 2 nd to 4 th finger (Figure 1). Lengths of the DPs and soft tissue extending distally from the most distal part of DPs (ST) were measured in a three-dimensional multiplanar reconstruction. Volumetric BMD and bone microarchitecture were analyzed using HR-pQCT scanner specific software at the distal radius. Figure 1. Results We included 40 patients with SSc of whom 13 had AO according to hand radiographs. The two groups had a similar distribution regarding age, sex, and BMI. Patients with AO had longer disease duration compared to patients without AO (med. 17 yrs. (IQR 7-20 yrs.) vs 3 yrs. (IQR 2-7 yrs.) ( P &lt;0.001)). One patient was excluded from the BMD analysis, and 21 (9%) DP and 20 (8%) soft tissue measurements were excluded due to motion-induced image degradation. A higher prevalence of calcinosis was observed in patients with AO ( n =11/13) compared to patients without AO ( n =11/27) ( P &lt;0.05). Patients with AO had more or larger calcifications according to our grading system (med. 2 (IQR 1-3) vs 0 (IQR 0-1)) ( P &lt;0.001). Grade 3 changes were observed in patients with AO ( n =6/13, 46%) but not in patients without AO. Furthermore, the patients with AO had shorter DPs on the 2nd finger on both hands (right P&lt;0.001; left P&lt;0.01) and less ST on the right 2nd, 3rd, and 4th (P&lt;0.01; P&lt;0.001; P&lt;0.01) as well as the left 3rd (P&lt;0.05). We observed no differences between bone volume ratio (med. 0.101 (IQR 0.068-0.143) vs 0.126 (IQR 0.104-0.141) ( P =0.38)), cortical BMD (med. 828 (IQR 774-853) vs 842 (IQR 762-882) ( P =0.60)), or trabecular BMD (med. 121 (IQR 82-172) vs 151.6 (IQR 125-170) ( P =0.36)). Yet, the patients with AO had a lower number of trabeculae ( P &lt;0.05) and a lower homogeneity of spacing between trabeculae ( P &lt;0.05) at distal radius. Conclusion Patients with AO had larger and a higher number of calcifications and had significantly shortened DPs and ST on several fingers assessed by HR-pQCT. A potential superiority compared with hand radiographs is yet to be established. Still, the modality could eventually prove useful in detecting and monitoring small hand lesions and facilitate earlier diagnosis and proper treatment among patients with SSc. References [1]Koutaissoff, S., et al., Hand radiological damage in systemic sclerosis: comparison with a control group and clinical and functional correlations. Semin Arthritis Rheum, 2011. 40(5): p. 455-60. [2]Marot, M., et al., Prevalence and predictive factors of osteoporosis in systemic sclerosis patients: a case-control study. Oncotarget, 2015. 6(17): p. 14865-73. Disclosure of Interests Frederik Cosedis Enevoldsen: None declared, Josephine Therkildsen: None declared, Rasmus Klose-Jensen: None declared, Katja Thorup Aaen: None declared, Amanda Lynggaard Riis: None declared, Klaus Soendergaard: None declared, Ellen-Margrethe Hauge Grant/research support from: Personal fees from MSD, Pfizer, UCB, and Sobi. Grants from Roche and Novartis.